When a change in the dependent variable could be due to participants' familiarity with the test, ...

When a change in the dependent variable could be due to participants' familiarity with the test, __________ is a threat to internal validity.
 
  a. attrition
  b. testing
  c. diffusion of treatment
  d. instrumentation

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In John's study, he knows that each participant had an equal probability of being placed into each of his conditions. John must have used .
 
  a. external validity.
  b. random assignment.
  c. systematic sampling.
  d. random sampling.

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Subject variables are true independent variables.
 
  Indicate whether the statement is true or false

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A research idea is broad and a research question is narrow.
 
  Indicate whether the statement is true or false

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You want to replicate Barlett et al.'s research on amount of blood in a video game and measures of aggression. Your independent variable has 4 levels: maximum blood, medium blood, low blood, and no blood.
 
  You want to conduct a between subjects design. How many total participants will you need if you want 10 participants in each level of the IV?
 
  a. 10
  b. 20
  c. 30
  d. 40